Apparatus and methods for using fiber optic arrays in optical communication systems

ABSTRACT

Systems and methods for optical communication that may be employed to couple together fiber optic arrays of two or more optical communication modules using parallel fiber optic connectors and physically distinct and signal-independent optical communication paths. The disclosed systems and methods may be employed to provide separate signal-independent communication paths having signal transport characteristics that meet standards required for single fiber single point-to-single point applications.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/967,847 filed Oct. 18, 2004, now U.S. Pat. No. 7,020,359 which is acontinuation of U.S. patent application Ser. No. 10/087,648, filed Mar.2002, now U.S. Pat. No. 6,816,642.

BACKGROUND OF THE INVENTION

The present invention relates generally to optical communications, andmore particularly to fiber optic communication systems.

Optical communication technologies are employed in a wide variety ofcommunication environments. Examples of such communication environmentsinclude, but are not limited to, telecommunications, networking, datacommunications, industrial communication links, medical communicationslinks, etc. In networking environments, fiber optics have traditionallybeen employed in the network core as long-haul backbones. More recently,fiber optic technologies have been implemented at the network edge,e.g., in metropolitan area network (“MAN”) and local area network(“LAN”) environments. Examples of other environments in which opticalcommunication technologies are being deployed include network operationcenters, corporate network backbone, central offices, and edge/coreaggregation points.

As optical communications have been implemented in edge environments, anincreased need has developed for optical interconnect equipment that iscapable of alleviating bandwidth bottlenecks by using increased portdensities to provide more links at higher speeds within a constrainedphysical infrastructure. At the same time that service providers areattempting to deploy such higher bandwidth solutions, they face marketconstraints that increasingly make such solutions more difficult toimplement, e.g., reduced capital budgets, physical space limitations,HVAC (heating, ventilation, and air conditioning) limitations,increasing power costs due to limited power grid capacity, etc.

Modern conventional optical communication infrastructures commonlyemploy 1310 nm-based optical transmission technology for short,immediate, and some long-range links, while more expensive 1550 nm-basedtechnologies are generally reserved to implement longer-haulrequirements, often using dense wavelength division multiplexing(“DWDM”). Single mode fiber 1310 nm optical technologies have beenemployed for short-reach (“SR”) and intermediate-reach (“IR”) linksusing the abundance of unused dark fiber available in existing networkinfrastructures, such as may be found in MAN infrastructures. In thisregard, 1310 nm-based optical solutions are denser and more powerefficient than 1550 nm-based DWDM solutions. Furthermore, it is lessexpensive to utilize a separate fiber and 1310 nm optics fortransmission of an additional signal in an environment where theseparate fiber is already installed and available.

However, despite the implementation of 1310 nm-based opticaltechnologies, service providers still face the problem of how to deploymore 1310 nm interconnects at higher speed and lower cost per bit withinthe same or smaller physical space, and in a manner that takes advantageof reductions that have been achieved in integrated circuit scale.Smaller systems consume less floor space and power, enablingtelecommunications companies to minimize lease expenses for equipmentspace. Shrinking system footprints also enable carriers to migrate tosmaller facilities located nearer to users at the network edge. Opticalconnectors and associated optical modules have been developed in anattempt to respond to market needs. For example, 1310 nm fiber opticcommunication technology is now commonly implemented using small formfactor (“SFF”) connectors, which support two optical fibers within aconnector width of approximately 0.55 inches. However, even with use ofSFF connector technology, port density improvements have not kept pacewith corresponding improvements in scale that have been achieved inintegrated circuit design.

BRIEF SUMMARY OF THE INVENTION

Disclosed herein are systems and methods for optical communication thatemploy parallel fiber optic arrays to couple together two or moreoptical communication modules via physically distinct andsignal-independent optical communication paths in which eachsignal-independent optical communication path is capable of transportingone or more signals that are separate and independent from other opticalcommunications paths. The disclosed systems and methods may beadvantageously implemented to provide a much denser and more powerefficient optical interconnect solution for high speed/multi-portoptical systems than is available using conventional technology and, indoing so, may be implemented to allow system providers to overcomeexisting barriers to improvements in density, power efficiency and costeffectiveness. The physically distinct and signal independent opticalcommunication paths provided by the disclosed systems and methods alsomake possible increased flexibility in system architecture. In onedisclosed embodiment, parallel fiber optic connectors may be employed incombination with fiber optic arrays to enable much higher port densitiesand greater power efficiency than is possible using existing SFF-baseddevices. For example, commercially available parallel fiber opticconnectors commonly employed in single point-to-point parallel ribbonfiber applications (e.g., conventional MTP™ connectors that support upto 12 single-mode fibers in a single ferrule and connector) may beemployed to provide separate signal-independent communication pathshaving transmission characteristics that meet the much more demandingstandards required for single fiber single point-to-single pointapplications, e.g., standards such as may be set by IEEE, ITU and ANSIstandards bodies. Surprisingly, such single point-to-point connectorsmay be used in the disclosed systems and methods to provide multiple(e.g., non-single point-to-single point) communication paths that arephysically distinct and signal-independent from each other while alsobeing standards-compliant for each path. In one embodiment, suchconnectors may also be employed in a manner to support or enable up tofour times the number of ports on a card edge as compared to analternative design based on small form factor devices.

In another disclosed embodiment, parallel fiber optic connectors may beemployed in combination with vertical-cavity surface-emitting lasers(“VCSELs”) to provide multiple signal-independent optical communicationpaths in a high density single mode configuration that offers smallersize and reduced power consumption at a lower cost than traditionalSFF-based implementations. Using VCSELs enables multiple opticaltransmitters to be integrated into a single transmit module to which aparallel fiber optic connector, such as an MTP™ connector, may becoupled to provide an independent optical transmitter for each fiberoptic port of an MTP™ connector array. In such an implementation, two ormore 1310 nm-based transmit and receive array modules (e.g., based on1310 nm VCSEL technology) may be coupled together, for example, usingMTP™ connectors in conjunction with industry standard single and/orduplex fiber connectors. When compared to conventional 1310 nm SFF-basedtransceivers, such an implementation may be used to realize system-levelimprovements such as increased system level densities, reduced powersupplies, elimination of cooling fans, lower system costs, smallersystem footprint for remote and/or space-restricted locations (e.g.,remotely located pedestals, distribution cabinets in a multi-tenant unitor corporate campus, elevated installations on utility poles, etc.),increased battery back up time for remote systems, and/or greatlysimplified fiber management.

Thus, the disclosed systems and methods may be advantageously used toenable many more signal-independent optical ports to be integrated intoa single optical communication system than is possible with existingoptical communication technologies such as conventional SFF-basedtechnology. Furthermore, benefits of lower cost per port and lower costper bit may be realized using the disclosed systems and methods becausethe cost of supporting functions including power supplies, fans, printedcircuit boards, and chassis may be spread across a larger number ofports.

Another benefit that may be additionally or alternatively realized usingthe disclosed systems and methods is simplification of the management offiber optic cables attached to an optical communication system thatincludes one or more optical communication modules. For example, in oneembodiment the bulk, weight, cost, and complexity associated with fiberoptic cabling may be greatly reduced by bundling multiple independentfibers into a single ribbon cable for coupling to an opticalcommunication module. Individual fibers of a single ribbon cable maythen be split apart or otherwise separated at a point removed from theoptical communication system, e.g., split out at a patch panel with asimple fan out cable assembly for routing to different locations.

In one respect, disclosed is a fiber optic communication assembly,including: an optical communication module having a plurality of atleast three fiber optic ports, the plurality of fiber optic ports beingconfigured as an array, at least a first one of the plurality of fiberoptic ports being signal-independent from at least a second one of thefiber optic ports; and a plurality of fiber optic conductors each havinga first end and a second end providing an optical communication paththerebetween, each of the plurality of fiber optic conductors beingcoupled at its first end to one of the plurality of fiber optic ports,the first ends of the plurality of fiber optic conductors being disposedin adjacent parallel relationship at the plurality of fiber optic ports.A first one of the fiber optic conductors of the fiber opticcommunication assembly may be coupled to the first one of the pluralityof fiber optic ports to form a first signal-independent opticalcommunication path, and a second one of the plurality of fiber opticconductors may be coupled to the second one of the plurality of fiberoptic ports to form a second signal independent optical communicationpath. The second end of the first fiber optic conductor may beconfigured to be disposed in remote physical relationship to the secondend of the second fiber optic conductor.

In another respect, disclosed herein is an optical communication system,including: a first optical communication module having a plurality of atleast three fiber optic ports, the plurality of fiber optic ports beingconfigured as an array, at least a first one of the plurality of fiberoptic ports being signal-independent from at least a second one of thefiber optic ports; and a plurality of fiber optic conductors each havinga first end and a second end providing an optical communication paththerebetween, each of the plurality of fiber optic conductors beingcoupled at its first end to one of the plurality of fiber optic ports,the first ends of the plurality of fiber optic conductors being disposedin adjacent parallel relationship at the plurality of fiber optic ports.A first one of the fiber optic conductors of the optical communicationsystem may be coupled to the first one of the plurality of fiber opticports to form a first signal-independent optical communication path, anda second one of the plurality of fiber optic conductors may be coupledto the second one of the plurality of fiber optic ports to form a secondsignal independent optical communication path. The second end of thefirst fiber optic conductor may be coupled to a first fiber optic portof a second communication module to form the first signal-independentoptical communication path between the first communication module andthe second communication module. The second end of the second fiberoptic conductor may be coupled to a first fiber optic port of a thirdcommunication module to form the second signal-independent opticalcommunication path between the first communication module and the thirdcommunication module.

In another respect, disclosed is a method of optical communication,including providing an optical communication module having a pluralityof at least three fiber optic ports, the plurality of fiber optic portsbeing configured as an array and being coupled to plurality of fiberoptic conductors each having a first end and a second end providing anoptical communication path therebetween, each of the plurality of fiberoptic conductors being coupled at its first end to one of the pluralityof fiber optic ports, the first ends of the plurality of fiber opticconductors being disposed in adjacent parallel relationship at theplurality of fiber optic ports, a first one of the fiber opticconductors being coupled to a first one of the plurality of fiber opticports to form a first optical communication path, and a second one ofthe plurality of fiber optic conductors being coupled to a second one ofthe plurality of fiber optic ports to form a second opticalcommunication path, the second end of the first fiber optic conductorbeing disposed in remote physical relationship to the second end of thesecond fiber optic conductor. The method of this embodiment may alsoinclude transmitting or receiving a first optical signal at the firstfiber optic port of the first optical communication module through thefirst optical conductor, the first optical signal beingsignal-independent from an optical signal transmitted or received at thesecond fiber optic port of the first optical communication module.

In another respect, disclosed herein is a fiber optic communicationassembly, including: an optical communication module having a pluralityof fiber optic ports, the plurality of fiber optic ports beingconfigured as a single-wafer array, at least a first one of theplurality of fiber optic ports being signal-independent from at least asecond one of the fiber optic ports; a plurality of fiber opticconductors each having a first end and a second end providing an opticalcommunication path therebetween, each of the plurality of fiber opticconductors being coupled at its first end to one of the plurality offiber optic ports, the first ends of the plurality of fiber opticconductors being disposed in adjacent parallel relationship at theplurality of fiber optic ports. A first one of the fiber opticconductors of the fiber optic communication assembly may be coupled tothe first one of the plurality of fiber optic ports to form a firstsignal-independent optical communication path, and a second one of theplurality of fiber optic conductors may be coupled to the second one ofthe plurality of fiber optic ports to form a second signal independentoptical communication path. The first signal-independent opticalcommunication path may be physically distinct from the secondsignal-independent optical communication path.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings which illustrate the best mode presently contemplatedfor carrying out the present invention:

FIG. 1 is a simplified representation of a fiber optic communicationassembly according to one embodiment of the disclosed system andmethods;

FIG. 2 illustrates optical signal variability as a function of distancefor a fiber optic communication system employing conventional singlepoint-to-point ribbon fiber cabling;

FIG. 3 illustrates optical signal variability as a function of distancefor an optical communication system employing multiplesignal-independent and physically distinct optical communication pathsaccording to one embodiment of the disclosed systems and methods;

FIG. 4 is a simplified representation of a fiber optic communicationssystem according to one embodiment of the disclosed systems and methods;

FIG. 5A is a simplified representation of another fiber opticcommunications system according to one embodiment of the disclosedsystems and methods;

FIG. 5B is a simplified representation of another fiber opticcommunications system according to one embodiment of the disclosedsystems and methods;

FIG. 6 is a perspective view of a SONET fiber optic metro system basedon conventional small form factor transceivers; and

FIG. 7 is a perspective view of a SONET fiber optic metro systemaccording to one embodiment of the disclosed systems and methods.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates one embodiment of a fiber optic communicationassembly 100 that includes an optical communication module 110 havingmultiple fiber optic ports 111 configured as an array 112. Multiplefiber optic conductors 120 are shown optically coupled to each of thefiber optic ports 111 of array 112. In this regard, a fiber opticconductor may be any combination of structure (e.g., fiber, filament,rod, etc.) and material (e.g., glass, plastic, etc.) suitable forconducting light waves from point to point. Although illustrated as asingle segment in FIG. 1, each of fiber optic conductors 120 may includeone or more individual fiber optic segments, optical connectors and/orother optical coupling devices coupled between its respective first end122 and second end 124.

As shown in FIG. 1, multiple fiber optic conductors 120 extend fromarray 112 in adjacent parallel relationship (i.e., extending from array112 in parallel or substantially parallel manner), and then diverge orotherwise separate so that each of multiple fiber optic conductors 120defines an optical communication path that is physically distinct, i.e.,they are no longer disposed in adjacent parallel relationship with otherfiber optic conductors 120 (e.g., not bundled together or disposed in aribbon fashion), and/or have lengths or paths that differ from otherfiber optic conductors 120. It will be understood that each of fiberoptic conductors 120 may include one or more individual fiber opticsegments, connectors and/or other optical coupling devices disposedbetween its respective first end 122 and second end 124. A physicallydistinct optical communication path may also be defined by a fiber opticconductor 120 having a different physical configuration than other fiberoptic conductors 120 (e.g., having differing number or type of fiberoptic segments, having differing number or type of connectors, having apassive module connected at second end 124 for splitting out multiplewavelengths, etc.), although this characteristic need not necessarily bepresent. In this regard, a fiber optic conductor 120 may be optionallyconfigured in one exemplary embodiment to communicate a plurality ofoptical signals (e.g., using wavelength division multiplexing (WDM),coarse WDM, DWDM, etc.), and may include a splitter and/or combiner atfirst end 122 and/or second end 124 as appropriate to split or combine aplurality of wavelengths for communication to or from given fiber opticports of an array 112.

As further illustrated in FIG. 1, second ends 124 of multiple fiberoptic conductors 120 may also be disposed in a variety of physicallyseparate remote locations (e.g., terminating in a manner that is otherthan adjacent and parallel). Examples of physically remote locations atwhich two or more fiber optic conductors 120 may terminate include, butare not limited to, non-adjacent fiber optic port locations on a commonoptical communication module or chassis, locations on different modulesor chassis in the same room or facility, locations in different rooms orfacilities in the same building, locations in different buildings,locations in different cities or towns, locations in different telephonecompany central office buildings, etc). Fiber optic communicationassembly 100 may be implemented alone or with other fiber opticcommunication assemblies for optical coupling purposes in a variety ofdifferent applications including, but not limited to, to makeconnections between two or more fiber optic arrays, to make backplaneinterconnections between multiple system modules, to makechassis-to-chassis interconnections, to make connections for arrays tosingle channel or multiple channel transmitters, receivers ortransceivers, etc.

Still referring to the embodiment of FIG. 1, optical communicationmodule 110 may be any optical communication device having multiple fiberoptic ports 111 configured in a fiber optic array 112 that is capable oftransmitting and/or receiving at least one signal-independent opticalsignal (e.g., single mode optical signal, multiple mode optical signal,etc.) in one of the fiber optic ports 111 of array 112. In this regard,a given fiber optic port 111 may be capable of transmitting or receivingan optical signal through a fiber optic conductor 120 that isindependent (e.g., separate and different) from an optical signal thatis simultaneously transmitted or received through another fiber opticconductor 120 by another fiber optic port 111 in the same fiber opticarray 112 (e.g., using multiple independent transmitters and/orreceivers coupled to the same array 112). For example, one fiber opticport 111 may transmit a signal that is independent and separate from asignal transmitted by another fiber optic port 111, and/or one fiberoptic port 111 may transmit a signal while another fiber optic port IIIin the same array 112 may receive a separate and independent signal. Itis possible that any one or more individual fiber optic ports 111 of afiber optic array 112 may be characterized as signal-independent, andthat a signal-independent fiber optic port may be coupled to arespective fiber optic conductor 120 to form a signal-independentoptical communication path. In one exemplary embodiment, each fiberoptic port 111 of fiber optic array 112 may be characterized as beingsignal-independent from all other fiber optic ports 111 in the samearray 112, and multiple fiber optic ports 111 may be coupled torespective multiple fiber optic conductors 120 to form multiplesignal-independent optical communication paths.

In the exemplary embodiment illustrated in FIG. 1, fiber optic array 112is shown having 12 fiber optic ports 111 and as being configured in a1×12 rectangular array. However, it will be understood that variousother array configurations may be employed having multiple fiber opticports configured to be coupled to multiple fiber optic conductors inadjacent parallel relationship. In one embodiment, a fiber optic arrayof an optical communication module may be characterized as having atleast two fiber optic ports configured in an adjacent disposedrelationship, alternatively as having at least three fiber optic portsconfigured in an adjacent disposed relationship, and furtheralternatively as having at least four fiber optic ports configured in anadjacent disposed relationship. Such an array may be of any suitablearray geometry, as necessary or desirable for a given application (e.g.,rectangular array, square array, circular array, irregular array, etc.).A rectangular or square fiber optic array may be configured with one ormore columns and one or more rows. Examples of suitable types ofrectangular or square arrays include, but are not limited to, single rowarrays (e.g., 1×4, 1×8, 1×12, etc.), single column arrays, and generaltwo dimensional arrays (e.g., 2×4, 2×8, 2×12, 6×12, etc.).

In the practice of the disclosed systems and methods, a fiber opticarray may be configured in any density suitable for use with fiber opticconductors to form physically distinct and signal-independent opticalcommunication paths in a manner such as described elsewhere herein. Inone exemplary embodiment, a fiber optic array may be configured to havea density of less than about 0.4 inch per port, alternatively to have adensity of less than about 0.3 inch per port, alternatively to have adensity of less than about 0.2 inch per port, and further alternativelyto have a density of about 0.1 inch per port. In another exemplaryembodiment, a fiber optic array may be configured to have a density ofless than about 0.1 inch per port, alternatively less than about 0.05inch per port, and further alternatively to have a density of about 0.02inch per port. It will be understood with benefit of this disclosurethat a given density may be achieved using fiber optic arrays suitablydimensioned to achieve the given density, for example, by employingsingle wafer arrays (e.g., having multiple lasers formed on the samedie, or one continuous wafer with multiple lasers disposed on it),although other types of arrays may be employed in other embodiments(e.g., having multiple laser packages at the die level and incorporatedinto a module).

As previously mentioned, optical communication module 110 may include anoptical transmitter array, an optical receiver array, or a combinationthereof (e.g., optical transceiver array) that has one or moresignal-independent fiber optic ports 111. In this regard, any opticalcommunication device having a fiber optic array suitable for signalindependent operation in one or more fiber optic ports may be employedas optical communication module 110. Exemplary types of opticalcommunication devices that may be employed as optical communicationmodule 110 include, but are not limited to, vertical-cavitysurface-emitting laser (VCSEL) fiber optic arrays, edge-emitting laserbased fiber optic arrays, PIN photo diode detector arrays, avalanchephoto diode detector arrays, LED-emitting diode fiber optic arrays, etc.Examples of suitable VCSEL fiber optic arrays that may be employedinclude, but are not limited to, 850-nm VCSEL arrays, 1310 nm VCSELarrays, 1550 nm VCSEL arrays, etc. Other examples of suitable VCSELfiber optic arrays that may be employed include, but are not limited to,VCSEL fiber optic arrays having a wavelength in the range of from about1260 nm to about 1660 nin, although VCSEL fiber optic arrays havingwavelengths of greater than about 1660 nni or less than about 1260 nmmay also be suitably employed. In one exemplary embodiment, opticalcommunication module 110 may be a 12-channel 1310 nm transmit arraymodule or 12-channel 1310 nm receive array module. Further informationon suitable VCSEL fiber optic array technology may be found described inU.S. Provisional Patent Application Ser. No. 10/122,707 filed Apr. 11,2002, and entitled “Long Wavelength Vertical Cavity Surface EmittingLaser” by Naone et al., the disclosure of which is incorporated hereinby reference.

Fiber optic conductors 120 may be provided together (e.g., packaged,laid out, arranged, bundled, etc.) at first end 122 in any mannersuitable for orienting conductors 120 in adjacent parallel relationshipfor coupling with respective fiber optic ports 111. In one embodiment,fiber optic conductors 120 may be provided together at first end 122 asa parallel ribbon cable. In such an embodiment, any type of parallelribbon cable may be employed that is suitable for coupling multiplefiber optic conductors to a corresponding suitable fiber optic array ina manner as described herein. Suitable parallel ribbon cables may beconfigured with any suitable number of individual fiber optic conductorsto meet a given application and/or may be available from a variety ofsources. Specific examples of suitable parallel ribbon cables include,but are not limited to, MTP™/MPO, MPX, SMC™, etc.

In the practice of the disclosed systems and methods, individual fiberoptic conductors 120 may be provided together at first end 122 with amultiple fiber connector suitable for interconnection with acorresponding mating multiple fiber connector on optical communicationdevice 110 so as to allow simultaneous coupling of individual fiberoptic conductors 120 with respective individual fiber optic ports 111(e.g., to connect an entire array 112 directly to a fiber ribbon cable).Specific examples of suitable multiple fiber connectors that may beemployed for interconnection of multiple fiber optic conductors 120 tomultiple fiber optic ports of array 112 include, but are not limited to,high density MTP™ connectors available from U.S. Connec of Hickory,N.C., MPX connectors, MPO connectors, SMC™ connectors, VF-45 connectors,etc. However, it will be understood that in other embodiments one ormore of multiple fiber optic conductors 120 may be coupled to respectivemultiple fiber optic ports of fiber optic array 112 using other suitabletype of connectors or using no connectors (e.g., conductors spliceddirectly into the ports). Furthermore, it is not necessary that multiplefiber optic conductors 120 be provided in the form of a parallel ribboncable at first end 122 for connection to optical communication module110, but instead may be provided as individual fiber optic conductorsthat are separately coupled to the fiber optic ports of array 112.

In one exemplary embodiment employing fiber ribbon cable and MTP™connectors, chassis-to-chassis coupling may be achieved using a directfiber ribbon cable link with MTP™ connectors on both chassis ends todeliver one or more independent optical signals between two chassiscomponents. Alternatively, the illustrated embodiment may beadvantageously employed to achieve a wide variety of systemconfigurations, e.g., to efficiently connect fiber optic arrays intoexisting fiber infrastructures, by employing ribbon cables that fan outfrom a single MTP™ interface of an optical communication module 110 intoindividual (e.g., LC, SC, FC, etc.) connectors at a patch panel (e.g.,at front-side or back-side side of patch panel). In the latterembodiment, one or more independent optical signals may be deliveredfrom a first optical communication module 110 to two or more otherseparate optical modules (not shown in FIG. 1), as in a manner that willbe described further herein.

As previously described, for embodiments such as those illustrated inFIG. 1, one or more optical ports of array 112 of optical communicationmodule 110 may be signal-independent. For example, optical communicationmodule 110 may be configured so that at least a portion the opticalports of fiber optic array 112 are each signal-independent and coupledto its own separate transmit laser or separate photodetector fortransmitting or receiving a separate optical signal through arespectively coupled fiber optic conductor 120. In such animplementation, one or more control signals may be provided tofacilitate signal independent operation for each of respective opticalfiber optic ports of array 112. For example, a transmit disable(Tx-Disable) signal may be employed on one or-more transmitting ports ofarray 112 to disable faulty or defective individual transmitters,without affecting other properly operating transmitters coupled to otherports of array 112. It will be understood that such a Tx-Disable signalmay be employed by an optical communication module 110 that isconfigured as optical communication transmitter module, or that isconfigured as an optical transceiver module in order to controloperation of individual transmit lasers employed therein. Similarly, aloss of signal (LOS) control signal may be employed on each receivingport of array 112 of an optical communication module 110 (e.g., opticalreceiving module, optical transceiving module) to facilitate independentoperations of each signal independent optical communication path throughan associated fiber optic conductor 120.

In one embodiment of the disclosed systems and methods, it is possibleto further facilitate signal-independent operation of one or moreoptical communication paths by enhancing channel isolation so as toreduce cross talk that may occur between individual fiber opticconductors 120 (e.g., caused by spill-over light from a laser into anadjacent fiber not directly coupled to that laser). This may beparticularly desirable in those embodiments where one or more fiberoptic conductors 120 vary in length from one or more other fiber opticconductors 120 coupled to the same fiber optic array 112, and/or whereone or more fiber optic conductors 120 have second ends 124 thatterminate in a location physically remote from the second ends 124 ofother fiber optic conductors 120. Under such conditions, adverse effectssuch as cross talk may be exacerbated by greatly increased attenuationof an incoming optical signal at a fiber optic receiving port III of anoptical communications module 110 coupled to a fiber optic conductor120. In this regard, incoming signal variability experienced by a singleoptical communication module 110 between two or more fiber opticconductors 120 that define physically distinct optical communicationpaths (e.g., having independent signals originating at physically remotelocations, having different lengths, etc.) is typically greater than theincoming signal variability experienced between multiple fiber opticconductors having the same length and that are routed in adjacentparallel relationship along their entire lengths, e.g., such as a fiberribbon cable used in a conventional single-point-to-single pointapplication employing a single high bandwidth transmitter and singlehigh bandwidth receiver.

FIG. 2 and FIG. 3 are representations of signal variability for multiplefiber optic conductors as a function of distance between fiber optictransmission ports and fiber optic receiver ports. In this regard, FIG.2 represents signal variability experienced between individual fiberoptic conductors that are arranged in adjacent parallel relationship(e.g., ribbon fiber cable) for single-point-to-single point opticalcommunication, e.g., from fiber optic transmission ports of the samefiber optic array to fiber optic receive ports of the same fiber opticarray. In contrast, FIG. 3 represents signal variability experiencedbetween individual fiber optic conductors that define physicallydistinct and signal independent optical communication paths, such as formultiple-point-to-single point optical communication, e.g., frommultiple fiber optic transmission ports positioned at physically remotesecond ends 124 through fiber optic conductors 120 to fiber opticreceive ports 111 of optical communication module 110. As may be seen bycomparing FIG. 2 with FIG. 3, fiber attenuation variability (B) is muchgreater between individual fiber conductors that define physicallydistinct optical communication paths than it is between individualparallel conductors of a single-point-to-single point ribbon fiber cableconfiguration, resulting in a much greater variability in incomingoptical signal strength (C) between different optical communicationpaths as experienced by a given optical communication module of amultiple-point-to-single point optical communication path configuration.It may also be seen from FIGS. 2 and 3 that maximum fiber attenuationand signal variability increases with distance between fiber optictransmission and receive ports, making the task of configuring a givenoptical communication module to accept such widely variable signals in astandards-compliant manner more difficult with increasing length ofoptical communication paths. Although illustrated with respect todistance, it will be understood that increases in signal variability mayadditionally or alternatively result from differing number and qualityof optical conductors and/or connectors that are employed to define oneor more optical communication paths of a given system.

In one embodiment of the disclosed systems and methods, a fiber opticcommunication assembly 100 may be further configured to provide one ormore standards-compliant optical communication paths using any systemconfiguration in which optical signals may be transmitted and/orreceived across optical conductors and, in one exemplary embodiment, maybe configured to provide standards compliance under signal variabilityconditions described and illustrated in relation to FIG. 3. In oneexample, the disclosed systems and methods may be implemented to enableoptical communication module 110 to transmit and/or receive opticalcommunication signals through optical conductors 120 that are compliantto signal-independent optical communication standards, e.g., as may beestablished by standards bodies such as the IEEE, ITU or ANSI standardsgroups. Specific examples of such signal-independent standards include,but are not limited to, IEEE 802.3z Gigabit Ethernet 1000 BASE-LXStandards, SONET Short-reach OC-1 through OC-48 standards, TelcordiaTechnologies GR-253 CoreSONET standards, ANSI T1, ESCON, etc. Suchstandards-compliant optical communication paths may be enabled, forexample, by using any suitable optical communication module 110 orcombination of multiple optical communication modules 110 that iscapable of achieving channel isolation and reduction in cross talksufficient to achieve optical bit error rate (“BER”) design objectivesnecessary to meet a given standard (e.g., despite wide incoming signalvariability that may be experienced in system configuration as describedand illustrated in relation to FIG. 3).

In one embodiment of the disclosed systems and methods, pairs of VCSELfiber optic transmit and PIN photodiode detector receive ports may beemployed to support signal compliance of independent incoming signalsfrom multiple and physically distinct optical communication paths thatexhibit a relatively large difference in signal variability by enhancingchannel isolation so as to reduce cross talk and preserve independentsignal integrity. For example, signal-independent andstandards-compliant optical communication paths through opticalconductors 120 may be enabled by configuring an optical communicationmodule 110 with a single mode VCSEL having spatially varying opticalloss to provide single-mode operation, such as described in U.S. patentapplication Ser. No. 09/587,074, filed Jun. 2, 2000, and entitled“Single Mode Vertical Cavity Surface Emitting Laser” by Scott et. al.,the disclosure of which is incorporated herein by reference. Such asingle mode VCSEL may be implemented, for example, as part of astandards-compliant optical communication transmitter module having aself adjusting data transmitter driver that is capable of monitoringcharacteristics of an optical data signal and that is further capable ofusing feedback (e.g., based on parameters such as BER, data eye,discreet optical data integrity parameters, and discreet opticalparameters) to adjust the optical quality of the laser output towardsoptimization in order to meet standards compliance. Such aself-adjusting data transmitter driver is described in U.S. patentapplication Ser. No. 10/ 60/262,620 filed Jan. 17, 2001, and entitled“Self-Adjusting Data Transmitter” by Yorks, the disclosure of which isincorporated herein by reference.

Alternatively, a photodetector may be implemented as part of a standardscompliant optical communication receiver module having anopto-electronic device configured as a photo detector and having anon-chip capacitor design that utilizes combinations of capacitors andresistors to reduce cross talk among adjacent detectors in fiber opticarrays. Such a technology is described in U.S. patent application Ser.No. 10/017,786 filed Nov. 30, 2001, and entitled “High Speed DetectorsHaving Integrated Electrical Components” by Lindemann et al., thedisclosure of which is incorporated herein by reference.

FIG. 4 illustrates one exemplary embodiment of an optical communicationsystem 400 having an optical communication transmitter module 410 inoptical signal communication with an optical communication receivermodule 420 via at least one optical conductor 402 providing asignal-independent optical communication path therebetween. Asillustrated in FIG. 4, optical communication transmitter module 410 isprovided with “m” number of multiple transmitter input signals 404, eachof which corresponds to a separate signal independent fiber optictransmitter port of fiber optic array 408 of optical communicationtransmitter module 410. A multiple fiber connector 406 is provided forconnecting individual optical conductors 402 in adjacent parallelrelationship to respective signal-independent fiber optic ports (notshown) of array 408. Similarly, multiple optical conductors 402 arecoupled to respective signal independent fiber optic ports (not shown)of fiber optic array 418 of optical communication receiver module 420using multiple fiber connector 416. An “n” number of multiple receiveroutput signals 414 corresponding to respective signal-independent fiberoptic ports of array 418 are provided for optical communication receivermodule 420 as illustrated. Although FIG. 4 illustrates an opticalcommunication transmitter module 410 coupled to an optical communicationreceiver module 420 via at least one optical conductor 402, it will beunderstood that either one or both of optical communication modules 410and 420 may be optical transceiver modules, e.g., with a fiber optictransmitter port of transceiver module 410 coupled to a fiber opticreceiver port of transceiver module 420. Further, it will be understoodthat modules 410 and 420 may be coupled together with two or moreoptical conductors 402 in a manner similar as illustrated for at leastone optical conductor of FIG. 4. In such a case, it will be understoodthat any two or more optical communication paths may be physicallydistinct from each other even though they are coupled between the sametwo modules.

In the embodiment illustrated in FIG. 4, any desired number of opticalconductors 402 may be coupled to fiber optic array ports of opticalcommunication transmitter module 410 and/or optical communicationreceiver module 420. Furthermore, it will be understood it is possiblethat a number of optical conductors 402 (e.g., 12) may be coupled tofiber optic array ports of optical communication transmitter module 410that differs from the number of optical conductors 402 (e.g., 8) coupledto fiber optic array ports of optical communications receiver module420. This may result, for example, where optical communicationtransmitter module 410 is provided with a different number of fiberoptic array ports than is optical communication receiver module 420,and/or when not all fiber optic array ports of one or both modules arecoupled to a respective optical conductor 402 (i.e., not all fiber opticports of a given module array need be used or coupled to an opticalconductor, nor do all optical conductors of a given multiple fiberconnector need be used or coupled to a fiber optic port). Furthermore,as will be illustrated and described further herein, it is also possiblethat only one of optical communication modules 410 and 420 may beconfigured with an array of multiple signal-independent fiber opticports, with the other module being alternatively configured to have asingle signal-independent fiber optic port coupled to a opticalconductor 402 via a single fiber connector, e.g., LC connector, SCconnector, FC connector, directly connected to an optical transmitter orreceiver through splices, etc.

In the embodiment illustrated in FIG. 4 intermediate fiber connectors430 are illustrated as being present within each of the opticalcommunication paths defined by optical conductors 402. It will beunderstood that intermediate fiber connectors 430 are optional and maynot be present in any given optical communication path defined by anoptical conductor 402, and/or that more than two intermediate fiberconnectors 430 may be present in any given optical communication pathdefined by an optical conductor 402. Intermediate fiber conductors maybe any type of connector suitable for coupling two or more fiber opticsegments together, alone or in parallel with other fiber optic segments.

Examples of intermediate fiber connectors include, but are not limitedto, patch panel connector, bulkhead feedthroughs, optical crossconnects, switches, etc. In one exemplary embodiment, an intermediatefiber connector 430 may be a patch panel that facilitates distributionor separation of optic conductors 120, e.g. transitioning from aparallel ribbon fiber cable configuration to a distributed andphysically distinct separate fiber configuration.

Further illustrated in FIG. 4 are “m” number of Tx-Disable controlsignals (e.g., one for each independent signal transmitted by opticalcommunication transmitter module 410). Similarly shown are “n” number ofLOS control signals (e.g., one for each independent signal received byoptical communication receiver module 420). These control signals may beadvantageously employed in a manner as previously described tofacilitate signal-independent operation for each of thesignal-independent fiber optic ports of arrays 408 and 418, and theirassociated signal-independent optical communication paths defined byoptical conductors 402.

FIG. 5A illustrates an exemplary fiber optic communication system 500that includes multiple optical communication transmitter modules (i.e.,510, 512, and 514) and multiple optical communication receiver modules(i.e., 520, 522, and 524) coupled together by multiple signalindependent optical conductors 502. It will be understood that thesystem configuration illustrated in FIG. 5A is exemplary only, and isillustrative of the types of fiber optic system configurations that maybe present in a given embodiment of the disclosed systems and methods.For example, it will be understood that any combination of two or moreof the optical communication transmitter modules and opticalcommunication receiver modules illustrated in FIG. 5A may be employedseparately or in combination with other optical communication modules asdesired to achieve a desired system configuration. Furthermore, it willbe understood that any one or more of modules 510, 512, 514, 520, 522,and/or 524 may be optical communication transceiver modules (e.g., oneor more separate receiver modules and/or transmitter modules coupled totransceiver module, one or more transceiver modules coupled to othertransceiver modules, etc.).

As illustrated in FIG. 5A, two or more optical communication transmittermodules (e.g., 510 and 512) having the same or different number ofsignal-independent fiber optic transmit ports may be coupled to two ormore optical communication receiver modules (e.g., 522 and 524) havingthe same or different number of signal-independent fiber optic receiverports, via one or more signal-independent optical communication pathsdefined by optical conductors 502 coupled between each given pair ofcoupled optical communication modules. Furthermore, an opticalcommunication transmitter module 510 having multiple signal-independentfiber optic ports may be coupled to an optical communication receivermodule 520 having a single fiber optic detector port. Likewise, anoptical communication transmitter module 514 having a single fiber optictransmit port may be coupled to an optical communication receiver module522 having multiple signal-independent fiber optic ports.

Not shown in FIG. 5A are other optical communication modules that may becoupled, for example, to optical communication transmitter module 510and optical communication receiver module 524 via signal-independentoptical communication paths defined by optical conductors 504. It willalso be understood with regard to FIG. 5A that it is possible thatinstead of being single fiber optic port modules, optical communicationtransmitter module 514 and/or optical communication receiver module 520may alternatively be optical communication modules having multiplesignal-independent fiber optic ports, but to which only one opticalconductor 502 is coupled.

In the embodiment of FIG. 5A, any suitable optical conductorconfiguration as previously described herein may be employed to coupletwo respective optical communication modules (e.g., opticalcommunication transmitter module to optical communication receivermodule, optical communication transmitter module to optical transceivermodule, optical communication receiver module to optical transceivermodule, optical transceiver module to optical transceiver module). Inthis regard, each optical conductor may define an optical communicationpath including one or more optical conductor segments that may or maynot be interconnected by one or more fiber optic connectors.Furthermore, each optical conductor may be coupled to a given opticalcommunication module via a connector (e.g., multiple fiber connector orsingle fiber connector as appropriate) or may be hardwired or spliceddirectly to fiber optic ports of a given optical communication module.

FIG. 5B illustrates another exemplary fiber optic communication system500 that includes multiple optical communication transmitter modules(i.e., 510, 512, and 514) and multiple optical communication receivermodules (i.e., 520, 522, and 524) coupled together by multiple signalindependent optical conductors 502 having intermediate fiber connectors530 that may include, for example, one or more patch panels thatfacilitate distribution or separation of optic conductors 120 in amanner as previously described.

The disclosed systems and methods described and illustrated herein maybe employed as part of any optical communication system that is utilizedto transmit and/or receive two or more signal-independent opticalsignals between at least two optical communication modules. Examples oftypes of implementation environments in which disclosed systems andmethods may be employed include, but are not limited to, networkapplications (e.g., LAN, MAN, WAN SAN, etc.), switch applications (e.g.,digital SONET, Ethernet, Fibre Channel, industrial control lines,internal and/or external optical interconnects in entertainmentequipment systems, etc.). Specific examples of network applications inwhich the disclosed systems and methods may be employed include, but arenot limited to, in the last mile network of a metropolitan area network,in a high speed hub and spoke distribution system (e.g., network, datacenter, or intersystem communication architecture), in a local areanetwork, in a tree-structure network, etc. Specific examples of switchapplications in which the disclosed systems and methods may be employedinclude, but are not limited to, in digital cross-connect switches,SONET drop multiplexers, Ethernet switches, IP routers, dense wavelengthdivision multiplexing transport equipment, multi-service protocolprovisioning platforms, Fibre Channel switches, aggregation equipment,Optical cross connect, etc.

FIG. 6 illustrates one example of a Synchronous Optical Network(“SONET”) metro system 600 based on conventional SFF transceivers 610mounted on the edges of multiple cards 620 of each of system components602 and 604 of system 600. As illustrated in FIG. 1, each SFFtransceiver 610 is coupled to a respective two-fiber cable 612. Each SFFtransceiver has a separate transmitter and receiver corresponding toeach of the two respective fibers within each cable 612. Thus, asillustrated in FIG. 6, a total of 16 SFF transceivers 610 provided bytwo system components 602 and 604 are required to provide 32 separateoptical communication paths per card 620 (i.e., 16 separate transmitpaths and 16 separate receive paths).

FIG. 7 illustrates a SONET metro system based on 1310 nm VCSEL fiberoptic array modules 710 according to one embodiment of the disclosedsystem and methods. As shown in FIG. 7, four fiber optic array modules710 are provided that interconnect with four fiber optic MTP™ connectors712 at the edges of multiple cards 720 of component 702 of system 700.Parallel fiber optic connectors 712 are in turn shown interconnected toparallel fiber optic ribbon cables 714, which serve to couple system 700to other optical communication modules or systems (not shown). A jumpercable 716 is shown provided on each card to interconnect each fiberoptic array module 710 with a respective fiber optic MTP™ connector 712.However, it will be understood that a module 710 may be alternativelymounted on the edge of a card 720, e.g., for direct interconnection witha respective fiber optic MTP™ connector 712, so that a jumper cable 716is not required.

In one exemplary implementation of FIG. 7, each fiber optic array module710 may be configured with eight fiber optic ports, and cables 712 and714 may each have eight fiber optic conductors. In one embodiment, twofiber optic array modules may be configured as optical communicationtransmitter modules and two fiber optic array modules may be configuredas optical communication receiver modules. As so configured, theembodiment illustrated in FIG. 7 is capable of providing 32 separatesignal-independent optical communication paths (i.e., 16 separatetransmit paths and 16 separate receive paths) per card 720 from onesystem component 702, eliminating the need for an extra system componentand its associated hardware and power needs (e.g., power supplies,cooling fans, etc.) required by conventional system 600. Furthermore, avisual comparison of conventional system 600 of FIG. 6 with system 700of FIG. 7 illustrates the greatly improved density and smaller overallsystem size possible with implementations of the disclosed systems andmethods. Thus, FIG. 7 illustrates the significant advantages that may beachieved using one embodiment of the disclosed systems and methods overconventional SONET metro systems based on SFF transceivers. It will beunderstood that the embodiment of FIG. 7 is exemplary only, and thatfurther increases in density and/or reduction in size are possible, forexample, by configuring fiber optic array module 710 to have more thaneight fiber optic ports (e.g., 12 or more fiber optic ports), and byconfiguring each of cables 712 and 714 with a number of fiber opticconductors (e.g., 12 or more fiber optic conductors) corresponding tothe number of fiber optic ports.

While the invention may be adaptable to various modifications andalternative forms, specific embodiments have been shown by way ofexample and described herein. However, it should be understood that theinvention is not intended to be limited to the particular formsdisclosed. Rather, the invention is to cover all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined by the appended claims. Moreover, the differentaspects of the disclosed apparatus, systems and methods may be utilizedin various combinations and/or independently. Thus the invention is notlimited to only those combinations shown herein, but rather may includeother combinations.

1. An optical communication system, comprising: a plurality of fiberoptic conductors, each of said plurality of fiber optic conductorshaving a first end and a second end, and an optical communication pathdefined between said first and second ends thereof, said first ends ofsaid plurality of fiber optic conductors being separated into at least afirst group and a second group; a first optical communication modulehaving a plurality of optoelectronic devices thereon, said plurality ofoptoelectronic devices being configured into at least a first array anda second array, wherein said first end of each of said fiber opticconductors in said first group is coupled to one of each of saidplurality of optoelectronic devices in said first array and said firstend of each of said fiber optic conductors in said second group iscoupled to one of each of said plurality of optoelectronic devices insaid second array; and a control device in communication with each ofsaid optoelectronic devices in said first and second arrays ofoptoelectronic devices, said control device capable of controlling eachof said optoelectronic devices separately and independently relative toone another whereby each optoelectronic device and its associated fiberoptic conductor forms an individual signal independent opticalcommunication path.
 2. The optical communication system of claim 1,wherein said control device controls at least one of said optoelectronicdevices using a protocol that is compliant with a first standard, andsaid control device controls the at least one other optoelectronicdevice using a protocol that is compliant with a second standard, saidfirst and second standards being different from each other.
 3. Theoptical communication system of claim 1, wherein said control devicecontrols at least one of said optoelectronic devices using a wavelengthdivision multiplexing protocol.
 4. The optical communication system ofclaim 1, wherein said array of optical communication transmitter modulescomprises an array of VCSEL optical communication modules having awavelength in the range of from about 1260 nm to about 1660 nm.